First described by Douglas Adams and later formalised by the German Pirate Party, Vogonism terms a manner of acting such that information is kept hidden in public sight. In case of complaints about the lack of information available, vogonists usually refer to the public availability of said hidden information.
A distinctive property of vogonism is the establishment of an inscrutable network of communication channels and modes, as well as inconsistent use of those: In that manner, information is avoided to be present where recipients expect it, even if other, related information already had been transmitted over the same channel.
In human societies, a vogonic information system excels in limiting the effective use of it to a small circle of insiders, all the while providing plausible deniability.
In computer science, the vogonic property can refer to both code that is written so sloppily and without regard to readability that only a tiny number of people (usually the Authors, and not even those after a couple of months have passed) can comprehend it, as well as to code that has problems understanding itself. An example for the latter case would be a high to very high percentage of data type conversions.
Being a universal concept, it applies to code styles and documentation as well as wikis and any other place where you can hang signs saying "Beware of the Tiger". Contrast Hoare Property.